Means for forming flat helicoidal structures



April 12, 1949. POTTER ETAL I 2,467,227

MEANS FOR FORMING FLAT HELICOIDAL STRUCTURES Filed June '7, 1946 "ENTOR.

RUSSELL OTTER Patented Apr. 12, 1949 UNITED STATES PATENT OFFICE MEANS FOR FORMING FLAT HELICOIDAL STRUCTURES Russell L. Potter and Ferris C. Huber, Detroit, Mich.

Application June 7, 1946, Serial No. 675,276

11 Claims. (01. 18-19) 1 2 This invention relates to a machine for form- Figure 4 is a section taken on the line IVIV ing a helicoidal structure from plastics materials, of Figure 2. and particularly for forming such a structure Figure 5 is a section taken on the line V-V of having a greater dimension in one transverse di- Figure 2. rection than it has in another transverse direc- 5 Figure 6 is a detail of the mandrel portion of tion. our device as used with thermoplastic material In the art of forming helicoidal structures from showing particularly the means for heating and metallic material, as wire, there has grown up a cooling the coiled plastic. number of highly developed mechanisms. How- Figure '7 is a section taken on the line VII-VII ever, in the forming of helicoidal structures from 10 of Figure 6. plastics material it has beenfound that the theory In providing a method and mechanism for upon which the wire handling mechanisms opermeeting the objects and purposes above outlined, ate is largely inapplicable so that substantially we have in general provided means by which a different means must be provided. This has been mandrel of appropriate cross-sectional shape is done to some extent for forming helicoidal strucrotated and while rotating receives a strip of tures of plastics material wherein the structures flexible plastics material, while properly timed have a circular cross-section, but such devices with said rotations a pushing head reciprocates do not work even with considerable modification on the mandrel pushing the coils therealong as where the structure to be formed has a substanthey are formed. It is best that this pushing tially greater dimension in one transverse direcoccurs as the strip being wound onto the mandrel tion than it has inanother transverse direction. is coming onto it on narrow side of the mandrel.

Thus there is presented a problem requiring Since, for a substantially rectangular mandrel, special treatment and treatment which must be this occurs twice with each rotation thereof, the upon a different theory of operation than anystructure being formed is preferably pushed twice thing known prior to this time. with each rotation of the mandrel. The material Accordingly, it is a major object of our invenwhen thermoplastic is then heated and subsetion to provide a machine for practicing said quently cooled to fix in coiled position. In the method, for forming from plastics material a drawings the device by which our invention may helicoidal structure in which the dimension in be pract c d s Shown Somewhat schematically one transverse direction is substantially greater inasmuch as the particular manner and form of than the dimension in another transverse direcholding the various parts in operative position tion. form no part of the invention and can be supplied A further object of our invention is to provide by any person acquainted with equipment of this a machine for forming a helicoidal structure as type. aforesaid which will provide a continuous pro- Referring now to the drawings there is shown duction of finished product. a suitably mounted rotatable main shaft 1 sup- A further object of our invention is to provide porting for rotation with it a sprocket 2. Adjaa machine for forming helicoidal structure as cent said shaft is a crank drivin S t 3 Su taforesaid from plastics material in which either ably supported on bearings 4 and 5, provided at thermosetting or thermoplastics material may be 40 its one end with a crank 6 and at its other end handled rapidly and efliciently. with a bevel gear I. Meshed with said bevel gear Other objects and purposes of our invention 1 is a second bevel r 8 mounted n a drivin will be apparent to those persons acquainted with shaft 9 which is in turn rotatably Sup o d by the methods and equipment of this type upon a. suitable bearings l0 and II. Also mounted on reading of the following disclosure and inspection said driving shaft 9 is a sprocket l2 having oneof the accompanying drawings. half the diameter of the sprocket 2, and a pulley In the drawings: l3. A suitable motor M of any convenient type Figure 1 represents a somewhat schematic, parfitted with a driving pulley I5 is operatively contially sectioned, plan view of the operating elenected by a suitable belt with said pulley l3. ments of my machine. Mounted slidably onto the main shaft l'is a Figure 2 represents a side, partially sectioned, driving sleeve 16 within which said shaft is perview of the portion of my machine in the region mitted to rotate and which is provided at one of the actual coil forming mechanism. .end with a lug l'l. Pivotally affixed to said lug F iFigurze 3 is a section taken on line III-III of is one end of a connecting bar l8 whose other gure v end is pivotally affixed to the crank 6, whereby rotation of the shaft upon which said crank is mounted will cause reciprocation of the driving sleeve I6 with respect to the shaft I. Also mounted slidably onto the main shaft I and adjacent the forward (leftward as appearing in the drawings) end of the driving sleeve I6 is a driven sleeve 20. Said driven sleeve has a recess 2| in one end which receives one end of the driving sleeve I6 thereinto in partially telescoping and rotatable relationship therewith. A spring holding anchor pin 22 extends through a suitable opening in the main shaft I and extends a substantially equal distance therefrom on each side of said shaft. Said pin may be threaded, or may in any other suitable manner be held in a fixed relationship to said shaft I. The pin extends through the sides of the driven sleeve through a pair of slots 23 and 24 suitably arranged in the opposite sides of said driven sleeve.

At the forward end of said driven sleeve is a portion 25 of reduced diameter for purposes appearing following.

A head sleeve 26 is provided cooperating with the extreme forward end of the driven sleeve 20, and receives in partial telescoping relationship therewith the reduced diameter portion 25 of the driven member 20 to which it is held by a set screw 29. A suitable pin 21 is affixed in each side of the said head sleeve 26 to which are affixed the springs 28, which springs are affixed at their respective other ends to each end of the anchor pin 22.

The main shaft I supports at its forward end the non-circular mandrel Ia for rotation on an axis coinciding with the axis extended of said shaft. The end 30 of the mandrel is attached to the shaft at a point which, as shown in Figures 1 and 2 is a short distance forward of the location of the anchor pin 22 and, further, is spaced at substantial distance from the inner face 3| of the recessed portion of the head member 26. The importance of this will appear hereinafter. While the mandrel may if desired be an integral continuation of the main shaft I, it preferably will be detachable as hereinafter described for replacement by mandrels of different sizes and/or cross-sectional shapes.

The extreme forward end of the head sleeve 26 is tapered and is preferably formed somewhat rounding as best shown in Figure 2.

Referring now to Figure 6 there appears a detailed illustration of the mandrel and the parts associated therewith for use with a thermoplastic material. The mandrel itself is here taken as of substantially rectangular cross-section although it will be evident that other noncircular forms may be used. Any convenient threaded means extending from the end of the mandrel may be provided for cooperation with a threaded opening in the end of the shaft I, by which a given mandrel may be held onto said shaft but will be readily replaceable. The mandrel will be tapered sufficiently to permit pushing of the coiled material therealong and the amount of such taper will vary according to the characteristics of the material being handled and the particular size and shape of the mandrel. As a specific but not limiting example it has been found that for a mandrel twelve inches long, onehalf inch wide and one-sixteenth of an inch thick a taper of 0.050 inch in twelve inches of length is satisfactory. A ring M mounted on any suitable base 42 surrounds the discharge end of the mandrel but is spaced therefrom suificientiv to permit the passage of the coiled material on said mandrel between the mandrel and said ring. The purpose of the ring is to prevent excessive sidewise flutter by the free end of the mandrel when same is in rapid rotation. A pipe 43 provided with a plurality of jets 44 is provided and supported in any convenient manner (not shown) for directing cooling fluid, such as water, in one or more streams as needed onto the coiled plastic at the end of the mandrel.

The broken lines 45 indicate the two extreme positions of the head sleeve 26 as it reciprocates on the mandrel.

Interposed between the point of application of the plastic strip to the mandrel and the cooling fluid jets 44 is a heater element 48. This may be made in any convenient manner but is here specifically shown, for illustrative purposes only, as a semi-cylindrical shell 49 of any refractory material, such as porcelain, supporting a plurality of heating coils 50 which partially surround the mandrel la. The said heating member is fixedly mounted so that the mandrel Ia rotates with respect thereto by which the entire plastic coil on the mandrel is uniformly heated. A suitable source of electric current (not shown) is operatively associated with said heater and a suitable source of cooling fluid (not shown) is operatively associated with the pipe 43.

Operation As the motor I4 is energized and rotates it will efiect rotation of the driving shaft 9, and through the bevel gears I and 8 it will cause rotation of the crank driving shaft 3 and circular movement of the crank 6. The bevel gears i and 8 being of equal size the crank 6 will make one revolution with each rotation of the driving shaft 9. Through the sprockets 2 and I2 and the connecting chain I9 the main shaft I will be caused to rotate, but due to the two-to-one ratio between the said sprockets the main shaft I will rotate only once for every two rotations of the driving shaft 9.

The circular movement of the crank pin 6 will act through the connecting bar I8 to impart reciprocating motion to the driving sleeve I6. On its forward stroke (leftward as appearing in the drawing) the said sleeve It will move the driven sleeve 20 in the same direction and it in turn will likewise move the head sleeve 26. When the driving sleeve I6 commences to move rearwardly (rightwardly as appearing in the drawing) the springs 28 being anchored to the anchor pin 22 will act against the fastening pins 21 to pull the head sleeve and the driven sleeve 20 backwardly to follow the driving sleeve I6 during its backwardly moving stroke.

During this operation, however, the main shaft I has been continuously rotating and through the anchor pin 22 acting against the walls of the slot 23 and 24 said anchor pin will cause the driven sleeve 20 and the head sleeve 26 to rotate with said shaft. As shown in Figures 2 and 5 the joint between the driving sleeve I6 and the driven sleeve 20 is both slidable and rotatable so that the driven sleeve 20 will be free to rotate with respect to the driving sleeve I 6.

Since the main shaft I in our illustrative em bodiment rotates at one half the speed of the crank driving shaft 3, it will be understood that the three sleeve members will move forwardly and backwardly twice with each rotation of the main shaft and corresponding rotation of the drive sleeve and head sleeve. It will be noted that the head sleeve 26, being internally shaped similarly to the non-circular mandrel will not pass lbackwardly onto the circularly cross-sectional main shaft 1. Hence the end point 30 of the mandrel must be far enough backwardly to clear said head sleeve 26 in its rearwardmost position. The circular opening within the driven sleeve 20 will, of course, pass over this part without difficulty.

With the mechanism operating as described, a strip of thermoplastic material 35, is fed onto the mandrel la at a suitable angle thereto to provide the proper pitch for the helix. By proper timing of the reciprocation of the sleeve members with respect to the rotational position of the mandrel la, it will be seen that the head sleeve 26 can be caused to move forward and contact the rearward face of the rearwardmost part of the helix and, at selected rotative positions of the main shaft I, and push the whole helicoidal structure in a forward, or leftward direction. Since, for the machine here shown, the head sleeve 26 will come forward in this manner twice for each rotation of the mandrel la it will be seen that this pushing operation can be obtained during the laying of the plastic strips across each'of the narrow sides of the mandrel, and this is the preferable manner of operation. However, it is possible and within the scope of our invention to permit the pushing action to occur at other points in the rotation of the mandrel, and even to occur only once for each such rotation. In fact, the amount of turning possible for the mandrel between successive pushing actions being a function of the friction between the plastic strip, and the mandrel, it is conceivable that the mandrel might in some cases make several rotations between such successive pushing actions.

The thermoplastic strip when cold is sufficiently flexible to bend closely around the mandrel.

It is in such position caused to pass the heater 48 where it is warmed, and hence softened, sufliciently to assume the coiled position as its permanent shape. Immediately thereafter it passes the cooling station, here the zone under the jets 44, where the material is cooled and thus set in its new, or coiled, shape. The coil may then be discharged immediately from the end of the mandrel into a suitable receptacle, or to other convenient receiving means.

Where thermosetting material is used, it Will be discharged directly onto the mandrel from an extruder, and the heater 48 and cooling means 44 will be omitted. By controlling the heat content of the plastics material so that it is very close to the setting point as it is wound around the mandrel, and occasionally additionally cooling the mandrel, it can be caused to set promptly upon being laid thereon and thus be sufficiently stiff to be pushed along the mandrel as above described without distortion.

, The feeding means for the plastics strip 35 are conventional and hence are not shown.

It will be evident that the particular form of mandrel la shown in Figure 3 is for illustrative purposes only and it may be varied widely with out departing from the scope of my invention. As here shown, variations in the form of the mandrel are limited to non-circular shapes, and having a rather substantially greater dimension in one transverse direction than in another transverse direction. However, it is entirely conceivable that appropriate modification can be made to apply the basic principles of our device to mandrels of circular cross-section with certain desirable advantages obtained in the forming of circular coils.

It will also be understood that many other details of the mechanism here illustrated and described may be widely varied according to choice or in order to meet certain particular conditions of operations, but which variations will be within the scope of my hereinafter appended claims excepting as said claims expressly provide otherwise.

We claim:

1. In means for forming a helicoidal structure having a transverse dimension in one direction greater than that in the other direction, the combination comprising: a main shaft having axially aligned and operatively associated therewith a mandrel of suitable cross-sectional contour; means for rotating said shaft and mandrel 'at a pre-selected rate of rotation; means slidable on said mandrel and reciprocating thereon in timed relation to the rotation of said mandrel for intermittently engaging a helicoidal structure wound on the mandrel and pushing same therealong, said slidable means being rotatable with said shaft and mandrel.

2. In means for forming a helicoidal structure the combination comprising: a rotatable shaft having a mandrel associated therewith as an axial extension thereof and rotatable with said shaft; reciprocable sliding means on and rotatable with s'aid'mandrel; means for rotating said shaft and means for reciprocating said sliding means, said two last-named means being so timed with respect to each other that the sleeve makes a selected number of complete reciprocating cycles with each rotation of said shaft.

3. In means for forming a helicoidal structure having a plurality of side portions of substantially greater radius than other side portions, the combination comprising: a rotatable shaft having a mandrel associated therewith as an axial extension thereof and rotatable with said shaft; reciprocable pushing means mounted slidably on and rotatable with said mandrel; means for rotating said shaft and means for effecting reciprocation of said pushing means; said last two named means being so timed with respect to each other that with each rotation of the shaft and mandrel the pushing means makes a number of reciprocations equal to the number of first greater than that in the other direction, the combination comprising: a rotatable shaft having a mandrel associated therewith as an axial extension thereof and rotatable with said shaft; a longitudinally slidable driving sleeve on said shaft and longitudinally slidable driven sleeve on said shaft; said driven sleeve being rotatable with respect to said driving sleeve; means for provid ing an elongated opening through at least one side of said driven sleeve and a pin afiixed in said shaft extending radially outwardly through said elongated opening; a head sleeve non-rotatably mounted on but slidable with respect to the mandrel and partially telescopically receiving an adjacent end of said driven sleeve; resilient means connected between said pin and said head sleeve for urging said head sleeve toward said pin; means for rotatably supporting said shaft and causing same to rotate at a pre-selected rate; means for reciprocating said driving sleeve at a pro-selected rate timed with respect to the rotation of said sleeve.

5. In means for forming a helicoidal structure having a plurality of side portions of substantially greater radius than other side portions, the combination comprising: a rotatable mandrel shaft having a mandrel associated therewith as an axial extension thereof and rotatable with said shaft; reciprocable pushing means mounted slidably on and rotatable with said mandrel; means for rotating said mandrel and means for efiecting reciprocation of said pushing means; said last two named means being so timed with respect to each other that with each rotation of the mandrel the pushing means makes a number of reciprocations equal to the number of first above named side portions.

6. In means for forming a helicoidal structure having a transverse dimension in one direction greater than that in the other direction, the combination comprising: a main shaft having axially aligned and operatively associated therewith a mandrel of selected cross-sectional contour; means for rotating said shaft and mandrel at a pre-selected rate of rotation; means slidable on and rotatable with said mandrel and reciprocating thereon in timed relation to the rotation of said mandrel for intermittently engaging a helicoidal structure wound on the mandrel and for pushing same therealong; means for heating said helicoidal structure and means for cooling said structure after the heating all while said structure is being urged along said mandrel, but without contact between the urging means and the heated portion of the coil.

7. In means for forming a helicoidal structure having a transverse dimension in one direction greater than that in the other direction, the combination comprising: a main shaft having axially aligned and operatively associated therewith a mandrel of suitable cross-sectional contour; means for rotating said shaft and mandrel at a pro-selected rate of rotation; means slidable on and rotatable with said mandrel and reciprocating thereon in timed relation to the rotation of said mandrel for intermittently engaging a helicoidal structure wound on the mandrel, said means engaging said structure along the greater dimension thereofand pushing same therealong.

8. In means for forming a helicoidal structure having a transverse dimension in one direction greater than that in the other direction, the combination comprising: a main shaft having axially aligned and operatively associated therewith a mandrel of suitable cross-sectional contour; means for rotating said shaft and mandrel at a pre-selected rate of rotation and for winding a plastic strip on said mandrel; pushing means slidable on and rotatable with said mandrel for intermittently engaging the helicoidal structure wound on the mandrel along the greater dimension of said structure and means for reciprocating said pushing means in such timed relation to the rotation of said mandrel that said plastic strip is pushed therealong each time it is being laid onto the narrow side of said mandrel.

9. In means for forming a helicoidal structure having a transverse dimension in one direction greater than that in the other direction, the combination comprising: a main shaft having axially aligned and operatively associated therewith a mandrel of suitable cross-sectional contourj means for rotating said shaft and mandrel at a pro-selected rate of rotation and for winding a plastic strip on said mandrel; means slidable on and rotatable with said mandrel, and reriprocating thereon in timed relation to the rotation of said mandrel for intermittently engaging a hellcoidal structure wound on the mandrel along the reater dimension of said structure and for pushing same therealong each time the plastic strip is being laid on to the narrow side of said mandrel; means for heating said helicoidal structure and means for cooling said structure after the heating all while said structure is being urged along said mandrel.

10. In means for forming a helicoidal structure having a transverse dimension in one direction greater than that in the other direction, the combination comprising: a main shaft having axially aligned and operatively associated therewith a mandrel of suitable cross-sectional contour; means for rotating said shaft and mandrel at a pre-selected rate of rotation; means slidable on said mandrel and reciprocating thereon in timed relation to the rotation of said mandrel for intermittently engaging a helicoidal structure wound on the mandrel and for pushing same therealong; means for heating said helicoidal structure and means for cooling said structure after the heating, without contact between the urging means and the heated portion of the coil.

11. In means for forming a helicoidal structure from a plastic material the combination: of a rotatable mandrel and means rotating same, said mandrel receiving at an angle to its axis a strip of said plastics material for forming said structure; means rotatable with said mandrel, and slidable thereon and with respect thereto, for pushing the structure on said mandrel along said mandrel intermittently in timed relation to the rotation of said mandrel,

RUSSELL L. POTTER. FERRIS C. HUBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 861,608 Richardson July 30, 1907 1,393,041 Robertson et al. Oct. 11, 1921 2,363,826 Yellin Nov. 28, 1944 2,388,401 Freundlich Nov. 6, 1945 2,393,058 Pierce et a1 Jan. 15, 1946 

